Re: [PATCH v6 6/8] crypto: x86/aesni: Remove glue function macro usage

Eric Biggers
2019-11-22T02:08:15Z

On Thu, Nov 21, 2019 at 05:03:32PM -0800, Kees Cook wrote:
> In order to remove the callsite function casts, regularize the function
> prototypes for helpers to avoid triggering Control-Flow Integrity checks
> during indirect function calls. Where needed, to avoid changes to
> pointer math, u8 pointers are internally cast back to u128 pointers.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> arch/x86/crypto/aesni-intel_asm.S | 8 +++---
> arch/x86/crypto/aesni-intel_glue.c | 45 ++++++++++++------------------
> 2 files changed, 22 insertions(+), 31 deletions(-)
>
> diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
> index e40bdf024ba7..89e5e574dc95 100644
> --- a/arch/x86/crypto/aesni-intel_asm.S
> +++ b/arch/x86/crypto/aesni-intel_asm.S
> @@ -1946,7 +1946,7 @@ ENTRY(aesni_set_key)
> ENDPROC(aesni_set_key)
>
> /*
> - * void aesni_enc(struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src)
> + * void aesni_enc(void *ctx, u8 *dst, const u8 *src)
> */

This doesn't exactly match the C prototype.

> ENTRY(aesni_enc)
> FRAME_BEGIN
> @@ -2137,7 +2137,7 @@ _aesni_enc4:
> ENDPROC(_aesni_enc4)
>
> /*
> - * void aesni_dec (struct crypto_aes_ctx *ctx, u8 *dst, const u8 *src)
> + * void aesni_dec (void *ctx, u8 *dst, const u8 *src)
> */
> ENTRY(aesni_dec)

Likewise.

> FRAME_BEGIN
> @@ -2726,8 +2726,8 @@ ENDPROC(aesni_ctr_enc)
> pxor CTR, IV;
>
> /*
> - * void aesni_xts_crypt8(struct crypto_aes_ctx *ctx, const u8 *dst, u8 *src,
> - * bool enc, u8 *iv)
> + * void aesni_xts_crypt8(void *ctx, u8 *dst, const u8 *src, bool enc,
> + * le128 *iv)
> */

Likewise. This one is particularly strange because the first argument was
changed to void * here, but in C it's 'const struct crypto_aes_ctx *ctx'.

- Eric